Stacked Doherty Amplifier Layout for EMI and Heat Dissipation
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Solution Overview
Problem
Existing high frequency amplifiers face challenges with heat dissipation and stability due to close proximity of driver and peak amplifiers, leading to potential electrical instability and oscillation.
Innovation Solution
A high frequency amplifier design featuring an asymmetrical Doherty amplifier with a two-stage structure, where the driver and peak amplifiers are stacked on separate circuit boards, with phase-adjusting circuits to ensure antiphase alignment of signals, and grounded metal layers for electromagnetic shielding, enhancing heat dissipation through contact with a base member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the driver amplifier and peak amplifier are mounted close to each other on the same circuit board, then the device size is reduced, but electrical instability and oscillation occur due to electromagnetic interference
Solution Approach 1:
The amplifier system is divided into separate modules: driver amplifier, carrier amplifier, and peak amplifier, each mounted on separate circuit boards or separated by grounding structures. This segmentation reduces electromagnetic interference while maintaining compact overall size through vertical stacking.
Solution Approach 2:
Grounding structures and shielding layers are introduced as intermediary elements between the driver amplifier and peak amplifier. These intermediaries provide electromagnetic isolation, preventing oscillation and instability while allowing the amplifiers to be positioned close together for miniaturization.
2Area of stationary object
If the driver amplifier, carrier amplifier, and peak amplifier are mounted on the same plane, then the circuit board area increases, but three-dimensional mounting is required for miniaturization
Solution Approach 1:
The mounting structure transitions from two-dimensional planar arrangement to three-dimensional vertical stacking. Circuit boards are stacked in layers with grounding structures and shielding layers interspersed, enabling miniaturization of the footprint area while managing electromagnetic interference through the additional vertical dimension.
Solution Approach 2:
Multiple circuit boards and functional modules are nested vertically within a compact housing structure. The driver amplifier, carrier amplifier, and peak amplifier are arranged in stacked layers, with each layer containing related components, creating a nested configuration that reduces overall device volume.
3Device complexity
If phase alignment is not properly adjusted between carrier amplifier and peak amplifier, then the circuit simplicity is maintained, but power efficiency decreases
Solution Approach 1:
Phase adjusting circuits are incorporated to dynamically control the phase relationship between the carrier amplifier and peak amplifier inputs. By adjusting the phase parameter, the system achieves optimal power efficiency through constructive interference at the output, while the automatic adjustment mechanisms minimize the impact on circuit simplicity.
Data Source
AI summary
A high frequency amplifier includes a base member, an amplifying device having a drain pad on a front surface and a rear surface mounted on the base member, a dielectric layer disposed to cover the amplifying device and to extend onto a region of the base member outside the amplifying device, and a first wiring layer provided on the dielectric layer. The dielectric layer includes a plurality of vias formed on the drain pad, and the first wiring layer covers all of the vias and is electrically connected to the drain pad through the vias.